Blade pitch adjustment



Filed Oct. 9', 1943 Fla. 5

' E. WILDHABER 2,460,559

BLADE PI'rcfi ADJUSTMENT 5 Sheets-Sheet l INVENTOR Feb. 1; 1949 E, wlLDHABER 2,460,559

BLADE PITCH ADJUSTMENT Filed Oct. 9, 1943 5 Sheet-Sheet 2 INVENTOR' I Err/Mt Feb. 1, 1949. I E, w 2,460,559

BLADE PITCH ADJUSTMENT Filed Oct. 9, 1943 5 Sheets-Sheet 5 we INVENTORL'Q' EWtWM 24A no A .Feb. 1, 1949. E, WILDHABE 2,460,559

I BLADE PITCH ADJUSTMENT Filed Oct. 9 1943 5 Sheets-Sheet 4 FIG; l9

FIG. '25 use Feb. 1, 1949 r E, w 2,460,559

BLADE PITCH ADJUSTMENT Filed Oct. 9, 1943 5 Sheets-Sheet 5 IN V EN TOR. ERNEST W/L DHA BER ATTORNEY i Patented Feb. 1, 1949 BLADE PITCH ADJUSTMENT Ernest Wildhaber, Brighton, N. Y. Application October 1943, Serial No. 505,675

My invention relates to the blade pitch adjustment of propellers, helicopter rotors, and

' other high speed rotary elements having blades adjustable on axes substantially perpendicular to the axis of rotation.

Such blades are pulled outwardly by very larg centrifugal inertia loads, which also tend to turn the blades about their centersof adjustment. The result is that the pitch adjustment mechanism is heavily loaded and that a substantial amount of energy is required for the blade pitch adjustment. Also a heavygand expensive design of said mechanism is necessary.

The purpose of the present invention is to avoid the heavy torque loads of the present pitch adjustment mechanism of conventional design, so that aJighter and less expensive mechanism may '24 Claims. (c1. rho-icon) be used, which furthermore reacts faster to required changes'of blade pitch. This is accomplished by modifying the blade adjustmentso that a blade not only turns about its adjustment.

center, but also moves slightly along said center.

The natural tendency of a blade is to turn towards low pitch position, and to move outwardly, away. from the axis of rotation, that is from the propeller axis. With the proposed arrangement a blade is forced inwardly, towards the center of rotation, when it turns toward low pitch position. Thus the tendency of the blade to turn toward low pitch position is counteracted by the centrifugal outward pull. A complete balance can be eflected, or if desired the tendency of a blade to turn towards low pitch position may be underbalanced or over-balanced. In the latter case the blades mayhave a slight tendency to move towards high pitch position.

The displacement required lengthwise of the blade centers is found to be quite small.

In one embodiment rollers are .journalledon the shank of a blade, and engage ways operatively forming part of the central hub. These ways are by correspondingly varying the proportion of the blade motion lengthwise of itsadjustment center a to its turning motion about said center. "In 'other words the adjustment motion of the blade is a 2 varies with the turning position., It is a motion of varying lead.

The number of rollers which can be provided I on a complete circumference depends on the adjustment angle for which the mechanism is designed. In some cases of airplane propellers the blade adjustment may be as large as 120.

Thiswould limit the number of the above-saidrollers to only two. Three rollers could give an adjustment through about 110, depending some- "pure rolling contact.

, In the preferred embodiments of my invention rolling elements are used somewhat like rollers of anti-friction bearings. They have a bodily motion difierent from the motion of either one of the two members whose relative motion is to be enforced thereby. Positive means are used for timing the position of the rolling elements to the rollers are balanced, and the positively driven cage member merelysaieguards the predetermined relative positions which would also be arrived at by the rolling contact.

The invention will be particularly described I as applied tov airplane propellers, but is also applicable to high speed ship propellers with adjustable blades, to helicopter rotors, and other rotors. In a well known type of helicopter rotor the blades may go through a cycle of adjustment with each'turn of the rotor. In such a case it is especially important to have the blade torque balanced. v

helical motion at any one instant, whose lead In the drawings:

Fig. l is a diagram explanatory of the principles I derlying the present invention.

Figures 2a to 2! inclusive are sections alon I lines 2-2'01 Fig. 3, showing various pitch settings helical of a blade, that is various turning angles, corresponding to the diagram of Fig. 1.

Fig. 3 is a partial and diagrammatic view of a four-bladed propeller, taken lengthwise of the propeller axis.

Fig. 4 is a side view corresponding to Fig. 3, and showing the blade adjustment about and along a substantiall radial center.

Fig. 5 is a diagrammatic view illustrative of one embodiment of the present invention.

Figures 6 to 8 are diagram explanatory of the principles, which underlie the preferred embodiments of my invention.

Fig. 9 is a development to a plane of the circumference of two circular members having multiple ways, with rolling elements therebetween, such as may be used in a preferred embodiment.

Fig. 10 is a partial development similar to Fig. 9, but intended for a smaller range of pitch adjustment.

Figures 11 and 12 are partial developments illustrative of another preferred embodiment.

Fig. 18 is a partial section laid through the blade adjustment center illustrative of a further modification.

Fig. 19 illustrates a further preferred embodiment, to be considered especially for large ranges of pitch adjustment. It is also a sectional view through the propeller axis and blade adjustment center.

Figures 20 to 23 are diagrams explanatory of a refinement.

Fig. 24 is an axial view of a circular member having multiple ways formed in accordance with said refinement, and of tapered rollers contacting with said ways.

Fig. 25 is a front elevational view corresponding to Fig. 24 and showing a pair of circular members for enforcing relative helical motion of varying lead, as desired in the embodiments of the present invention for balancing the blade torque.

Fig. 26 is a more or less diagrammatic view showing in development the rollers and the ways illustrated in Fig. 15 which serve to hold the propeller blade and the nut, which is secured thereto, in the direction opposite to the direction of centrifugal pull.

Fig. 27 is a fragmentary sectional view taken, like Fig. 15, through the propeller axis and furl3 and propeller axis H. The adjustment about center It changes the pitch of the propeller blade. According to the present invention this turning adjustment is accompanied by a corresponding displacement of the blade along said center of adjustment so that the centrifugal pull of the blade acts to completely or partly balance the centrifugal torque, that is the torque caused by centrifugal inertia loads. This torque varies with different turning positions of the blade.

Diagram Fig. 1 shows the nature of the change. The ordinates of curve I'I are proportional to the torque at a given speed of rotation. These ordinates are plotted in terms of the turning angle of the blade on its aXis of adjustment l5, and particularly in terms of the turning angle of a mean section 2-2 of the blade.

The cause of the centrifugal torque is known. and is further shown in Fig. 20. All the elements of the blade section are subjected to centrifugal inertia loads, which are radial to the propeller axis ll. They are also perpendicular to the axis Ii in the projection Fig. 20. Thus the elements at opposite blade ends are under the influence of centrifugal inertia loads in the direction of arrows i 8, l8, which exert a torque on the blade about its adjustment center IS. The same condition exists to a varying degree for other mass elements of the blade section, and for other blade sections perpendicular to adjustment center i5. This torque tends to turn the blade towards low pitch position, that is towards the position shown in Fig. 2b. No torque is exerted on the blade in ther illustrating one way in which the rollers of Fig. 26 may be assembled with the ways of one of the nuts which cooperate with these rollers.

Fig. 28 is a fragmentary view, looking in the direction of the propeller axis taken from the left-hand side of Fig. 15 or Fig. 27, and illustrating the engagement of the roller shown with the ways of the nuts of a three-blade type propeller constructed according to this invention.

In Figures 1 to 4 numeral ii denotes the axis of a propeller I: having a hub l3 and blades ll mounted for adjustment about and along axes or centers it, which are substantially radial to hub this position, nor is there any torque exerted in the position shown in Fig. 2}, which is apart from the zero position Fig. 212. Maximum torque is exerted in an intermediate position, see Fig. 2d. A somewhat smaller torque, given by ordinate i 9-20, is exerted in position Fig. 20. In the position Fig. 2a the torque has been reversed.

The torque varies therefore substantially like the ordinates of the trigonometrical sine function of an angle double the turning angle of the blade. In other words it varies substantially in aharmonic manner.

To balance this torque at all positions of the turning motion of the blade on its adjustment center a motion along said center is provided. For complete balance the rate of said endwise motion, that is the instantaneous lead of the relative motion should be proportional to said torque.

Let :1 denote the blade torque in proportion to the centrifugal pull, that is the (fractional) number of inch pounds per pound of centrifugal radial load. Complete balance between the centrifugal torque and the centrifugal pull of a blade is obtained when for an infinitesimal displacement from a given position the energy received from one equals the energy consumed by the other. Energy received from the torque when the blade is turned towards zero position through say a millionth of a full turn equals one millionth of (21a) while the energy consumed by forcing the blade inwardly at an instantaneous lead L is one millionth of L. The two energies being equal means L=21ra The corresponding lead angle x at a mean or average radius A from the adjustment center may be computed in the conventional manner of com pnting lead angles as L tan X=m=2 7 give leads and lead angles varying with the blade plane of the drawing in a translatory manner,

instantaneous leads. It is evident to tilt! ilharmonic curve if curve I! is one.

' il when measured'from the extension of dotted by an amount shown exaggerated.

operation the rollers can be considered as jourleiigthwise of said center.

' amen s" a "These two equations applyto all'positions and position.

It is found that the lead angles required'are quite-small. Thus-for (i=3; 4:3": tanx=.066.6

h=3 49'. Curve 2i. Fig. 1, shows the endwise'displacement of a blade in terms of its turning angles, computed in known manner from the aforesaid I. miliar with mathematics that curve 2| isalsc a If it is desired to retain some unbalance between I the centrifugal torque and the centrifugal pull,

for instance if it is desired to overbalance the said torque so that the blade tends to turn towards high pitch position, a constant amount may be added to leads given bycurve l'l. The required leads then correspond to the ordinates 0! curve line 22 rather than from the full line. Curve 2iis then'also modified accordingly as well understood.

- cated by the reduced width of the blade outline in this view. It is seen that the blade is disposed further inwardly in the position of lower pitch, 1

' Fig. 5 -illustrates one way of making use of the aforesaid-principles. This embodiment can be considered as an intermediate step leading to the spreferred-embodiments disclosed hereafter.

Blade'shank 23 is threaded into a nut 24 and locked therein in a predetermined turning positionby means not shown-Operatively nut 24 is then a part of the blade. It contains a plurality of radial pins 25 formed integral with it, on which rollers 26- are iournalled' For the purposes of nalled on'the blade. Rollers 26 engage multiple ways provided on a circular member 21, which also acts as a guide for the motion of nut 24. Another circular member, 26, may engage the rollers on the opposite side. It is of less importance insofar as it carries no load during operation. Both circular members are rigidly secured to hub l3 which rotates on axis ii of the propeller, member 21 by'externalsplines or teeth which match internal splines or teeth provided on hub i3.

The blade' adjustment may be operated from tral bevel gear 30 concentric with the propeller M axis Ii, bevel gears 3| and spur pinions 32. A bevel gear 8| and a spur pinion 32 are rigidly secured to or integral with a radial shaft suitably mounted parallel to the adjustment center of the blade. Spur pinion 32 meshes with internal gear teeth provided on nut 24 and is thereby enabled to turn the blade on its center of adjustment while its straight teeth permit motion'of the blade curved lengthwise profile, and are movable inthe u so that a straight-line of a member remains par- ,allel to its initial position. Members 34, 46 can 7 be-considered as developments to a plane of concentric cylindrical sections of a pair of concentric circular members to be described hereafter with reference to Fig. 16. ways 31, II are engaged by a rolling element or roller 8!. Contact is at diametrically opposite points of the roller, so that the twopoints of contact havea joint normal 46 Fig. 6, which may correspond to the mean operating position, and a predetermined relative motion of the two members 66, II, that is a predetermined relationship between the lateral motion andthe motion perpendicular to the straight or plane ends 42, 43 of the members 36', 36. Inasmuch as said two members-are identical, their relative motion with respect to roller axis or center 44 is-equal and one half of the relative motion between themselves. The shape of ways 31, 34 is therefore such as may be swept out by-a milling cutter or grinding wheel embodying the shape of the roller,"when its member 35 or 36 is fed past in the aforesaid motion, that is in a relative path in all respects one half of the total relative path of said two members. The cutter describes the surface of the roller, as it rotates rapidly on its axis for cutting, and sweeps out the way required for the roller. In operation the roller of course turns differently on its center, namely-just so much as to roll without sliding on its ways. Thus the various relative positions are arrived at with pure rolling.

Fig. 6 and Fig. 7 show two difierent positions of members 35, 36 with respect to a fixed center 44 of the roller. Fig. 8 shows a fixed member 36, as actually used in accordance with my invention. The position shown in full lines is the same as in Fig. 6; and the dotted relative position is the same as shown in Fig. 7. Member 36 has moved to dotted position 36, for the full amount of its relative motion with respect to.

' The roller has moved to dotted position 39', its

center having moved through half the amount of relative motion of members 35, 36.

This feature that the rollers move only half as much as the movable guide member 36 is of prime importance, for it results in shorter ways as compared with the embodiment of Fig. 5, and in more rollers on the circumference. Thus a total turning angle of of the blade and of member'36 causes the rollers to move through only 60 about the blade adjustment center, so

. that as many as five rollers could be used on the circumference. v

Fig. 9 illustrates this condition. It shows a trifle more than one full circumference developed into a plane. Roller center 44' is actually a repetition of roller center 44, and their distance represents a full circumference.

Circular members 45, 46 contain-multiple ways which are equallyspaced and contain curved lengthwise profiles 41, representative of the'desired helical motion of varying lead. The slope of said profiles is shown about normal, whereas in Figures '6 to 8 the slope is shown exaggerated.

Fig. 10 is a partial development similar to Fig. 9, but intended for a smaller range of relative motion between the two circular members 48, 49;

for a pitch adjustment about half as much, that is about 60. Accordingly the multiple ways 50 can be made shorter, and more rollers can be used on the circumference, namely about nine.

Fig. .11 and Fig. 12 illustrate two positions of an embodiment in which the number of rollers provided on the circumference has been increased by using two sets of rollers in series. with this arrangement the full load is carried by each 01' said two sets. The relative motion is however split up, so that shorter ways are required, and more rollers can be used in each set. The proportion is as shown in comparison with Fig. 9, based on the same pitch adjustment range of about 120. Here about nine rollers can be provided on the circumference as compared with five.

The two sets of rollers engage multiple ways provided on circular members 52, 53, 54, comprising two end members 52, 54 and an intermediate member 53 having multiple ways formed on both sides. Member 52 is shown stationary. The other end member moves from position 54, Fig. 11, to position 54', Fig. 12, for the full amount of relative motion. The intermediate member moves from position 53, Fig. 11, to position 53, Fig. 12. Its motion is one half of the motion of end member 54'; as will be readily understood from the foregoing. The relative motion of the roller centers with respect to their ways is a quarter of the motion of end member 54. The absolute motion of the roller centers, or the bodily motion of the rollers, is one quarter of the motion of end member 54, .for the roller set 55, and three quarters of said motion for the roller set 55.

With this embodiment the problem of large pitch adjustment ranges can be conveniently solved even for very large loads.

Figures 9 to 12 can also be considered as a cylindrical section concentric with the adjustment center and developed into a plane.

Fig. 13 is a conical development of circular guide members of the type shown in the embodiment of Fig. 17. It can also be considered as a developed conical section concentric with the blade adjustment and perpendicular to the roller axes, like section A-A of Fig. 17.

In this case the relative motion between the roller centers and the circular members 58, 59 about and along the adjustment center is not exactly equal. In other words the rollers do not move bodily at exactly halt the speed of member 59, when member 58 is stationary, as is readily understood.

When the roller centers are first assumed fixed, as in Fig. 6 and Fig. 7, member 59 turns a little faster than member 58, namely at a ratio inversely proportional to the distance of the respective rolling points 60, 6| from the center of development. This center is also the center of circle 62 which passes through the roller centers. Rolling contact is effected when the peripheral motions are the same on both circular members 58, 59, which means that their turning motions about the center of development, or inactuality about the adjustment center, are unequal when the points of rolling contact are at different distances from the center of the turning motion.

with member 58 of larcerradius held stationmy. the relative motions are still the same as in the case when the roller centers are fixed; and the rollers then move bodily about said turning center at a1rate a little less than half the rate of motion of member 59, to be determined as aforesaid from the rules of planetary motion.

Aside from this difference, the principles underlying the tapered arrangement. as referred to in Fig. 13, are exactly the same as in the arrangements described with reference to Figures 6 to 12. Designs for large and for small pitch setting ranges may be made with the some considerations. Also two sets of rollers may be disposed in series or otherwise if desired.

Preferably the rollers are held in position by a cage member, which is omitted in the diagrams Figures 6 to 13, and which may rotatably hold the rollers for instance by means of pins passin through the centers of the rollers. In the proposed application the rollers are highly stressed and subjected to elastic deflection. Hg, 14 illustrates a special pin shape which may be used to avoid any substantial backlash between the pin and roller. Without load the roller is of circular shape, as shown in full lines. Heavy loads deflect the roller to an oval shape as shown exaggerated by dotted lines 63. The shown shape of pin 64 contacts with both. shapes practically without backlash, with its four well rounded corners. Fig. 15 illustrates one of the preferred embodiments of my invention. Blade 65 has a threaded end 66, which fits into a nut 67. It is secured to said nut in a predetermined position, which can be controlled by a pair of face clutches. A partial development of these clutches is shown in Fig, 16 at a larger scale. One'clutch comprises teeth 68 provided at the outer end of nut 51, and mating teeth 69 provided on an intermediate sleeve member ,Ill. The other clutch' comprises teeth 1| formed on the opposite side of sleeve member 70, and mating teeth 12 provided on another sleeve member 13. The latter also contains internal splines, which match short external splines 14 provided on the blade. The two clutches have large and difierent numbers or teeth. For instance their tooth numbers may diifer by one tooth, and are used in known manner in combination to exactly obtain a predetermined blade position.

After the blade has been threaded into nut 61, it is locked in its predetermined position by sliding sleeve 13 along splines ll to effect engagement of both clutches at the proper position of sleeve member 10. The clutches are maintained in engagement by a nut 15, which engages a fine thread provided on the outside of splines 74.

Nut 61 contains multiple ways 16 disposed on a flange-like projection Tl. Said ways are engaged by rollers 18, which also engage ways 19 of a circular member which is splined at 8| to the propgler hub 82. Hub 82 rotatm on the propeller axis Circular member 80 is further secured to hub 82 with light bolts omitted in the drawing, and operatively forms part of the hub. This member and nut 61 represent the circular members previously referred to, which contain multiple ways of curved profile in a cylindrical section concentric with the center of adjustment, and also in a view perpendicular to said center. Such a view is indicated in dotted lines I6, 19'. The two circuiar members and rollers ll act as guides for en- 7 forcing a predetermined helical motion of varying lead.

In operation the centrifugal pull of blade 55 keeps the rollers under pressure, which then together with said members control the position of the blade. Nut 61 and blade 65 are held also in opposite direction, namely by a pair of conical rollers or abutments 85, ll concentric with the .propelleraxis83. .On. account of said coneentricity'the same vided on nut 81, whose shape is such as to produce the same helical motion of varying lead as circular members 88, 81 and rollers 18.. Rollers 88, 88 are self centering and can be ioumalled on each other, especially in axial direction. If embodied. .as abutments they may be simply bolted together. These rollers can be used for preloadin'g, if desired. Otherwise they carry very little load, and none during flight.

Figs. 26 to 28 inclusive illustrate in detail the engagement of rollers 88 and 88 with the ways 81 1 and 88, respectively, with whichthe rollers co operate. Since. the ways 81 and 88 are shapedv to produce the same helical motion of varying lead as the ways 18 and 18 of nut 81 and member 88, respectively, the lead of the ways 81 and 88 is identical with the total lead of the ways 18 and 19, and this lead has, therefore. a substantially harmonic relationship with twice the tuming angle of a blade. In other words, the shape repeats for each 180 degrees, and, inasmuch as the rollers 88.and 88 are 180 degrees apart, the two ways 81 and 88 are identical with each other I and can be made to Join each other smoothly,

their propeller axis 83, the rollers 88 and 88 will contact all of the ways 81 and 88 of the several nuts 81 which are secured to the several blades it of the propeller. This is illustrated in Fig. 28

where a three-blade type propeller is shown. Here the roller 88 makes contact at three points with the three identical ways 81 of the three identical nuts 81 which are connected, respectively,

. with the three identical blades it orthe propeller. Similarly, the roller 88 will make simulroller centers. The ratio of, the two spur gear reductions is one to two in'the embodiment shown taneous contact with the three ways 88 of these three nuts. On account of their three-point contact, the three rollers 85 and 88 are self-centering and can be journaled on'each other.

Fig. 27 shows one way of mounting the rollers 88 and 88. Here roller 88 is integral with a sleeve 89 which telescopes rotatably into the hub portion I I8 of roller 85. A nut H8 which threads onto sleeve 89 serves to hold the rollers in assembled position after they have been engaged with the ways 81 and 88, respectively.

in Fig. 15, so that the cage member turns half as much about thecenter of, adjustment as nut 81 does.

When the member comprising spur pinions 8|, 94 and bevel gear 88 is turned on its axis, blade 85 aswell as cage member 98 are turned on the adjustment center of the blade, and are also moved lengthwise of said center through the guide means described. Their spur teeth thereby slide endwise on the teeth of said spur pinions,

which are mounted in an axially fixed position. The teeth have to be made long enough so that a sufiicient engagement is retained in all positions.

If desired a pivotal connection between blade 88 and nut 81 may be substituted for the rigid connection shown. That is the blade may be hinged to the nut. Such connection does however not form part of the present invention.

Fig. 17 shows a further preferred embodiment of my invention. This embodiment differs from the one shown in Fig. 15 by the tapered arrangement of the rollers 18.

Blade 85 is secured to nut 91 in the manner above described. Nut- 81 contains multiple ways 88' of curved profile arranged at an external taper on projection 88. These ways are engaged by rollers 18, which on their opposite side engage ways 98 disposed at'an internal taper on .a circular member 98. This member is rigidly about their joint shaft 88, The ratio of the turning motion of cage member |8i and nut 91 is I here not exactly one to two. It may be determined in the manner previously described.

- Blade pitch adjustment is effected by means of a spur pinion I85 which meshes with internal spur teeth provided at the lower end of nut 81.

I Said pinion is driven by means of a bevel gear I88 coaxial with the propeller axis 83, and a-mating bevel gear I81 coaxial with said pinion and dis- 1 posed to move in unison with it. The member In Fig. 15 and Fig. 1'1 tapered rollers '18 are I shown, namely conical rollers having straight profiles in their axial section. Tapered rollers are subjected to endwise thrust. To balance said thrust a flange 98 is provided on the roller, which contacts with its conical side 9| with a projection 01 side wall provided at the ways of the circular members 80, 81.

To change the pitch of blade 88 nut 81 is turned by. means ota spur pinion 9|, which engages teeth provided on the projection 11 of nut 81. Ordinarily straight teeth are used, and broadly comprising pinion I85 and bevel gear, I81 is journalled on centers which are axially fixed. This drive for operating the blade pitch adjustment, or the drive shown in Fig. 15 may be used interchangeably.

teeth of constant profile including helical teeth,

namely teeth whose mesh is unaffected by relative axial displacement of the mating gear; members.

Pinion 9| is driven from any suitable known 4 source through a central bevel gear 82 coaxial with the propeller axis 88. Bevel gear 82 meshes with a bevel gear 93 connected to or integral with pinion 9|. A further pinion 88 of smaller diameter is also connected to or integral with pinion 9|, and meshes with spur teeth provided on the cage member 88, which mo'vesin unison with the Nut 9'1 may also be driven by linkage or other means, especially in the case of moderate pitch adjustment, such as for instance on helicopter rotors. I

Circular members 98, 99 and rollers 18 hold nut 91 and thereby blade against the centrifugal pull. The blade is held in opposite direction by conical rollers |l8 coaxial with the propeller axis 83 and engaging multiple ways Ill provided on projection 98 of nut 91. The ways I may be similar in constructionto the ways 81 and 88 of Figs. 15 and 26 to 28 inclusive, and the conical rollers H8 engage these ways in a manner similar to the manner of engagement of the rollers 88 and 88 with the ways 81 and 88.

' Various types of rolling elements may be used between the circular members which guide the motion about and along the adjustment center.

Fig. 18 is a partial section similar to Fig. 11, and which shows a cylindrical roller H2 used between a pair of ways of circular members 8, I ll.

2,4eo,esa

1 i Thrust along the roller axis is thereby avoided. On the other hand rolling is accompanied by some sliding at the ends of the roller.

In the embodiment illustrated in Fig. 19 a pinrality of coaxial cylindrical rollers of reduced width are used between the ways of circular members I22, I23. The coaxial rollers may then turn at a different rate on their centers, in accordance with the peripheral velocity of the ways at different distances-from the adjustment center. Thus outside roller III will'turn faster than inside roller III; and the rolling action is thereby improved as compared with the solid cylindrical roller.

Other types of rolling elements which may be employed are for instance balls and barrel type rollers.

Fig. 19 further illustrates the use of a plurality of sets of rolling elements in series, that is one after the other. The two sets shown at H8, H3 roll on multiple ways provided on three circular and concentric members, namely on member I20 rigidly secured to hub I2I; on member I22 secured to the blade, and on intermediate member I23 having multiple ways I24, I25 formed onboth sides. Nut member I22 is held further by two conical rollers I26 coaxial with the propeller axis 03 and which engage ways I28 provided on said nut member. Rollers I26 are like rollers 35 and 06, and ways I23 are like ways 81 and of Figs. 15 and 26 to 28 inclusive.

Blade pitch adjustment is efiected by a spur pinion I30, which, meshes with gear teeth I3! provided on the outside of said nut member I22.

Formed integral with spur pinion I30 is a bevel gear I32, which is driven from a central bevel gear I33. Also formed integral with spur pinion I30 are spur pinions I34; I35, I36 of gradually smaller diameter, which serve for positive timing of the rollers. and which mesh with spur gear teeth provided on cage member I30, on intermediate circular member I23, and on cage member I30. The ratios of the spur gears may be determined in accordance with the principles already disclosed. Teeth do not have to be providedall around the circumference on the driven members, and for this reason fractional tooth numbers per full circumference are acceptable, so that any desired ratios may be obtained without difllculty.

The member comprising said spur pinions and bevel gear I32 is mounted in an axially fixed position in propeller hub I2I.

A refinement will now be described with reference to Figures 20 to 23, which further improves the rolling contact. This refinement applies broadly to combined motions about and along an axis, that is to helical motions of varying lead and even of constant lead.

Diagram Fig. 20 is a view taken along adjustment center I43 of a cylindrical roller I44 having a radial axis or center I45. Fig. 20 is a view along said axis or center I45.

The two circular members which have a mode-- termined relative motion about and alongcenter I43 are indicated only by their points of contact I40, I" with the, middle section of roller 4. These points are disposed diagonally opposite on the roller surface.

Let us consider the relative motion with respect to a stationary roller center I45.

As the roller turns on its center I45, its points move in the plane of Fig. 21 in peripheral direction, that is their instantaneous velocity at the P ints of contact is in the direction of arrows 146, i411. At the same points of contact the instantaneous velocity of said two members is about and along center I43, that is along arrows I46", I41" respectively. In the view of Fig. 21 these arrows seemingly coincide with the arrows I46, I45", but Fig. 20 shows their different directions. In this figure they appear perpendicular to radii i43-I48 and ids-4'41. In view of this difierence of direction true rolling without sliding cannot exist in this combination. This is true also for other rolling elements, conical rollers, barrel type rollers, balls used in a helical motion of varying or constant lead.

For the shown direction of rotation of the roller, namely along arrow I 49, the friction caused by sliding tends to pull the, rollers inwardly at both points of contact, that i towards center 3. when rotating in the opposite direction, the friction tends to pull the rollers outwardly.-

I have found a cure for this condition, and a way for obtaining pure rolling at points I46, I41. It consists in bodily moving the roller as it rotates on its center, namely in the direction of said center. when the rollers rotate in the direction of arrow I49 and tend to be drawn inwardly, true rolling at points I 46, I41 can be obtained by bodily moving the rollers inwardly at the rate of sliding when in an axially fixed position.. When rotating 'in opposite direction, they are bodily moved outwardly. The rate of this bodily motion is only small, but nevertheless quite advantagenus. It is a fraction only of the peripheral relative motion between said circular members and point I53 of the roller center. This fraction can be demonstrated to be equal to the trigonometrical tangent of angle 3, tan B, where p denotes angle I-l43-I46 of Fig. 20.

On account of thi bodily motion the rollers describe a spiral path relatively to said circular members, the radial lead of which changes with the relative axial lead of said -two members and is substantially proportional to said axial lead. It is also zero at the positions of zero axial lead. At such a position said path'appears in peripheral direction in a view along center I43.

The same considerations elements, such as the tapered roller IBI' shown in Figures22,23. TheseflguresaresimilartoFigures 20 and 21, and the same numerals have been used to designate the same quantities.

Tapered rollers can be made to roll on their entire active surface, as in antifriction bearings.

An axial view of a circular member constructed in accordance with the disclosed refinement is afforded by Fig. 24, which also shows the tapered rollers I54 which engage the multiple ways I30 of the circular member. Fig. 25 is a corresponding front view of a pair of circular members I57, I53 and the rollers disposed therebetween. The cage member is omitted for simplicity. It is desi ned here to permit moderate axial motion of the rollers.

The ways I55 are seen to extend along spirals of small radial lead, see Fig. 24, which varies along the ways, the end surface I of each way bein arranged to extend along a spiral which is of slight varying lead about the axis I5 of the blade, The r quired axial movement of the rollers is obtained by engagement of the thrust flanges ii! of the rollers with the end surfaces I of the ways- The described refinement may be applied also to tapered arrangements of the rollers, and to the embodiments described with reference to Fisures app y to other rolling 13 15, 17 to {19. They can be considered also detail of said preferred embodiments.

Numerous changes and modifications may be made in my invention without departing from its spirit, by simply applying current knowledge and practice. The appended claims are relied upon to cover such changes and modifications. When the term propeller is used in the claims it is intended to cover and include not only the drive propellers for airplanes, but helicopter rotors and other rotary members having adjustable blades.

I claim:

'1. Blade pitch adjustment, comprising a rotatable hub, a plurality of blades mounted in said hub on substantially radial centers for adjustment about and along said centers, the mounting means of ablade comprising a pair of circular members having multiple ways equally spaced about their axes, rolling elements engaging said ways, a cage member for holding saidrolling elements in :positiom -meaiis for turning "one-'- of said-circular Zm'embe'rs onus axis-"and positive means for turning the cage member at a reduced rate as compared with said one member.

2. Blade pitch adjustment, comprising a rotatable hub, a plurality of blades mounted in said hub on substantially radial centers for adjustment about and along said centers in a helical path of varying lead, the mounting means of a blade comprising two circular members having multiple ways arranged about their axes, rolling elements therebetween, means for positively timing said rolling elements to the relative turning position of said two members, said two members being secured to said hub and a blade respectively, and means separate from said timing means for turning the blade and the circular member connected therewith.

3. Blade pitch adjustment, comprising a rotatable hub, a plurality of blades mounted in said hub on substantially radial centers for adjustment about and along said centers, the mountin means of a blade comprising two circular members having multiple ways arranged about their axes, rolling elements therebetween, one of said members being secured to said hub, the other member being secured to a blade, gear teeth operatively forming part of said other member, a cage member for holding said rolling elements in position, gear teeth operatively forming part of said cage member, two pinions of different diameters jointly rotatable on a common axis and meshing with said two sets of gear teeth, and means for turning said pinions. v

4. Blade pitch adjustment, comprising a rotatable hub, a plurality of blades mounted in said hub on substantially radial centers for adjustment about and along said centers, the mounting.

means of a blade comprising circular members having multiple ways arranged about their axes, rne of said members being secured to said hub, another of said members being secured to a blade, an intermediate member having multiple ways formed on both sides, two sets of rolling elements disposed between said three members, two cages for holding said two sets of rolling elements, gear teeth forming operative parts of said two cages and of two of said three members, four pinions of different diameter jointly rotatable on a com-' mon axis and meshing with said gear teeth, and means for turning said pinions.

5. A propeller, comprising a rotary hub, a plurality of blades, each of which is mounted on said hub for adjustment on an axis extending outwardly from the hub, and means for adjustmg each blade in a helical path of varying lead about its axis comprising a face cam member secured to the blade coaxially therewith, a second.

face cam member secured to said hub, a rolling element for engaging said face cam members, means for turning the blade on its axis, and a train of gearing, including a gear which is secured coaxially with and to the blade and a gear which is operatively connected to the rolling element for revolving the rolling element about the axis of the blade simultaneously with the tuming motion of the blade but at a different rate from the turning motion of the blade.

6. A propeller, comprising a rotary hub, a plurality of blades, each of which is mounted on said hub for adjustment about and along an axis extending substantially radially of the hub, and means for adjusting each blade about its axis in a helical path of varying lead comprising a roller and'apair of face cam members, one of said three last named parts being secured to the blade and another to the hub, said face cam members being mounted coaxial of the blade and each having convex and concave profile portions in a cylindrical section coaxial of the blade axis, and said roller being mounted between said cam members to engage said cam surfaces at diametrically opposite points continuously during its roll, means for turning the blade on its axis, and means for simultaneously revolving the roller about the axis of the blade but at a different rate from the turning motion of the blade.

7. A propeller, comprising a rotary hub, a plurality of blades, each of which is mounted on said hub for adjustment in a helical path of varying lead about and along an axis which projects outwardly from the hub, and means for effecting the adjustmentof each blade comprising a pair of face cam members which are mounted coaxial of the axis of adjustment of the blade and which have cam surfaces of concave and convex profile shape in a cylindrical section coaxial of said axis, a plurality of rolling elements mounted between said cam surfaces, each of which engages said cam surfaces continuously at diametrically opposite points as it rolls, a cage in which the rolling elements are mounted for rotation, means for turning the blade on its axis, and means for simultaneously revolving said cage about said axis but at a different rate from the turnin motion of the blade.

8. A propeller, comprising a rotary hub, a plurailty of blades, each of which is mounted on said hub for adjustment about and along an axis which is radial of the hub, means for efiecting adjustment of each blade in a helical path of varying lead comprising a plurality of pairs of face cam members which are coaxial of the blade axis, one of which is secured to the blade and another to the hub and others of which are inter mediate said two, the cam members of a pair having cam surfaces that are of curved profile shape in a cylindrical section coaxial of the blade, a set of rolling elements for engaging the cam surfaces of each pair of cam members, each of the rolling elements engaging its pair of cam surfaces continuously at diametrically opposite points as it rolls, means for turning the blade on its axis, means for simultaneously revolving each set of rolling elements about said. axis at a different rate from each other set and at a different rate from the rate of turning of the blade, and means for simultaneously turning the intermediate cam members about said axis at a different rate from the blade and from the sets of rolling elements.

9.. A- propeller, comprising a rotary hub, a plu= rality of blades mounted on the hub for adjustment about and along an axis extending radially of the hub, and means for adjusting each blade about its radial axis in a helical path of varying lead comprising a pair of cam members, one of which is secured to the blade and the other to the hub, said cam members being mounted cog axial of the blade axis and having face cam surfaces which are of curved profile shape in a cylin drical section coaxial of the blade axis, tapered rollers mounted between said cam members to engage the cam surfaces continuously at diametrically opposite points as they roll, each of the tapered rollers having a thrust flange formed on it at one end, means on the cam members for engaging said thrust-flanges to counteract the axial thrust of the rollers as they roll on the cam members, and means for turning the blade on its axis.

10. A propeller, comprising a rotary hub, a pinrality of blades mounted on the hub for adjustment about and along an axis projecting outwardly from the hub, and means for adjusting each blade about its axis in a helical path of varying lead comprising a pair of cam members and a roller, one of said three last named part being secured to the hub and another to the blade, said cam members being mounted coaxia' of the blade axis and having face cam surface: which are of curved profile in a cylindrical sec tion coaxial of the blade axis, said roller being mounted between said cam members to engage said cam surfaces continuously at diametrically opposite points as it rolls when the blade is rotated, means for turning the blade on its axis,

and means for moving the roller bodily along itsv axis as it rolls.

11. A propeller, comprising a rotary hub, a plurality of blades mounted on the hub for adjustment about and' along an axis extending radially of the axis of the hub, and means for adjusting each blade about its axis in a helical path of varying lead comprising a pair of cam members, one of which is secured to the hub and the other to the blade, said cam members being mounted coaxial of the blade axis and having face cam surfaces which are of curved profile in a cylindrical section coaxial of the blade axis, a roller mounted between said cam surfaces to engage the cam surfaces at diametrically opposite points and to roll on said cam surfaces about the blade axis when the blade is rotated, means for turning the blade on its axis, means for moving the roller bodily along its axis as it rotates at a varying proportion to the turning motion of the blade, and means for revolving the roller about the blade axis simultaneously with the turning motion of the blade but at a different rate from the turning motion of the blade.

12. A propeller, comprising a rotary hub, a plurality of blades mounted on the hub for adjustment about and along an axis projecting outwardly from the hub, means for adjusting each blade about its axis in a helical path of varying lead comprising a pair of cam members, one of which is secured to the hub and the other to the blade, said cam members being mounted coaxial of the blade axis and having face cam surfaces which are of curved profile shape in a cylindrical section coaxial of the blade axis, a plurality of rollers mounted with their axes extending radially of the blade axis to engage the cam surfaces at diametrically opposite points and to roll on said cam surfaces about the blade axis when the 3 blade is rotated, means for turning the blade on its axis, and means for moving each roller bodily in a spiral path along its axis as it rotates, the radial lead of said spiral path varying in proportion to the axial leadof the cam surfaces.

13. A propeller, comprising a rotary hub, a plurality of blades mounted on the hub for adjustment on axes extending radially or the hub, and means for adjusting each of said blades about and along its axis comprising a pair of face cam members which are mounted coaxial of the blade and one of which is'securedto the hub and the other of which is secured to the blade, rolling elements mounted between said face cam members to engage the cam surfaces of said members to take the centrifugal outward pull of the blade, and means for turning the blade on its axis, and means for holding the second named face cam members of all blades in engagement with the rolling elements that cooperate therewith to hold the blade in the direction opposite to the direction of centrifugal pull, comprising a cam surface which is coaxial of each blade and is operatively part of said blade and which corresponds to the cam surfaces on the cammembers. and a rolling element which is mounted coaxially of the hub and which has simultaneous engagement with all of the last named cam surfaces of the several blades.

14. A propeller, comprising a rotary hub, a plurality of blades, each of which is mounted on the hub for adjustment about and along an axis projecting outwardly from the hub, means for adlusting each blade about its axis in a helical path of varying lead comprising a pair of face cam members, one of which is secured to the hub and the other to the blade, a plurality of rollers mounted between said face cam members to roll thereon. means for turning the blade on its axis, means for simultaneously rolling the rollers about said axis at a different rate from the turning motion of the blade, said rollers being bored axially and pins mounted within the bores of said rollers for connecting the rollers to said rolling means to effect roll of the rollers on actuation of said means.

15. A propeller, comprising a rotatable hub, a plurality of blades mounted in said hub for adiustment about and along axes extending substantially radially of the hub, and means for moving each blade about its radial axis in a helical path of varying lead, comprising means for turning the blade about its radial axis, two members mounted coaxial of said axis and having multiple ways of equal number arranged about said axis, the ways of both members having varying inclination to a plane perpendicular to said axis, and a plurality of rolling elements mounted between said members to-engage opposed ways simultaneously at diametrically opposite points and roll thereon, one of said members being secured to said hub and the other to the blade, and a train of gearing for rotating said rolling elements about said axis in timed relation to the turning movement of said blade, said gearing comprising a gear, which is secured coaxially with and to the blade, and a gear whose axis lies in a plane containing the blade axis and which is operatively connected to the rolling elements.

16. A propeller, comprising a rotatable hub, a plurality of blades mounted in said hub on axes, which extend substantially radially of the hub, for adjustment about and along said axes, and means for effecting said adjustment of each blade comprising a pair of circular members mounted which extend substantially radially of the hub, for adjustment about and along said faxes, and meansfor effecting adjustment of each'fblade comprising a pair of circuIaz-"members'mounted coaxial oi the blade axis andhaving multiple ways of equal number arranged about said axis,

a set of rolling elements disposed between said members to engage and roll on said ways, each of said ways having a varying lead so that when the blade is rotated a relative axial displacement of said members at a varying rate is produced coordinated with their relative turning position about the blade axis, the lead of each way having a substantially harmonic relationship with twice the relative turning angle.

18. A propeller, comprising a rotatable hub, a

plurality of blades, each of which is mounted in said hub on an axis, which extends substantially radially of the hub, for adjustment about and along said axis, and means for effecting said adjustment comprising two end rings, an intermediate ring interposed between the two end rings, said and rings having ways formed on their sides which face said intermediate ring being provided with ways on both sides, one of the end rings being connected with the hub and the other with the blade, two sets of rolling elements interposed, respectively, between each end ring and the intermediate ring, the opposed ways of the rings being arranged in pairs coordinated each with a rolling element, said two sets of rollin elements being disposed in series to reduce the length of said pairs of ways, positive means for timing the position of the rolling elements tothe turning position of said blade, and means for turning said blade about said axis, said ways being formed with a varying lead.

19. A propeller, comprising a rotatable hub, a plurality of blades mounted in said hub on axes, which extend substantially radially of the hub, for adjustment about and along said axes, and means for effecting the adjustment of each blade comprising a pair of members mounted coaxially of said axis and having multiple ways arranged about said axis, rolling elements disposed betweensaid members to engage said ways, each way being disposed spirally about the axis of its memher and being inclined to a plane perpendicular to said axis to guide its rolling element along a path extending radially as well as peripherally and axially of said member, and means for turning said blades.

20. Guide means for enforcing motion about and along an axis at a predetermined relationship, comprising a pair of concentric members, a way provided on each of said members, a rolling element disposed between'said ways and engaging said ways to transmit load, each way being disposed spirally about the axis of its member and being inclined to a plane perpendicular to the axis of said member to guide said rolling element under full load along a path extending radially as well as peripherally and axially of said member, to obtain improved rolling action.

21. A propeller, comprising a rotatable hub, a

plurality of blades mounted in said hub on axes, which extend substantially radially of the axis of the hub, for adjustment about and along said axes, and means for eflecting adjustment of each blade about its radial axis comprising two members which are coaxial of said axis and which are operatively part of said hub and of said blade respectively, ways provided on the opposed faces of said members, rolling elements disposed between said ways and engaging said ways to take the centrifugal outward pull of said blade, and different means for holding said blade in the opposite direction, comprising a cam surface operatively part of said blade and a further member which is provided with a surface of revolution that is concentric with the axis of rotation of said hub and that engages said cam surface.

22. A propeller, comprising a rotatable hub, a plurality of blades, each of which is mounted in said hub on 'an axis, which extends substantially radially of the hub, for adjustment about and along said axis, and means for effecting said adiustment of each blade in a helical path of varying lead comprising means for turning said blade about its axis, two members operatively part of said hub and of said blade respectively, and which are coaxial of said axis, said members being provided with ways on their opposed faces which are of curved profile in a cylindrical section coaxial of the blade, an equal number of ways being provided on both said members, rolling elements disposed between the ways of said members and 'each engaging said ways simultaneously and continuously at diametrically opposite points during its rolling movement, and positive means for timing the position of the rollingv elements to the relative turning position of said two members.

23. A propeller, comprising a rotatable hub, a plurality of blades, each of which is mounted in said hub on an axis, which extends substantially radially of the hub, for adjustment about and along said axis, and means for effecting adjustment of each blade in a helical path of varying lead comprising means for turning said blade about said axis, two members mounted coaxial of said axis and which are operatively part of said hub and of said blade respectively, and which have ways formed on their opposed faces which are equal in number and arranged in pairs, rolling elements disposed between the ways of said members and each engaging a pair of opposed ways simultaneously and continuously at diametrically opposite points during its rolling movement, said ways having varying inclinations to a plane perpendicular to said axis but the two opposed ways of a pair having portions of identical inclination and of identical length and positive means for timing the position of the rolling elements to the relative turning position of said two members.

24. A propeller, comprising a rotatable hub, a plurality of blades, each of which is mounted in said hub on an axis,-which extends substantially radially of the hub, for adjustment about and along said axis, and means for eifecting adjustment of each blade in a helical path of varying lead comprising means for turning the blade about its axis, two members mounted coaxial of said axis and operatively part of said hub and of said blade respectively, and which have ways formed on their opposed faces, an equal number of ways being provided on both said members, rolling ele ments disposed between-the ways of said members and each engaging said ways simultaneously and continuously at diametrically opposite points durmemos ing its roiling movement, the two ways simul- Em taneously engaged by a rolling element having R ENCES mm identical working portions, that have varying The following references are 0! record in the radial and axial leads, said leads being in a subfile of this patent: stantially constant proportion, and positive 5 m I m m means for timing the position of the rolling ele- STA PA ments to the relative turning position of said two Number Name members. 1,887,543 Chilton Nov. 15, 1982 2,283,364 Gemeny Feb. 25, 1941 ERNEST WIIDHABER. FOREIGN W Number Country Date 95,613 Sweden Mar. 2, 1939 336,4?9 Great Britain Oct. 16, 1930 768,458 ce Aug. '1, 1931 

